docs: def _get_hanging_wall_distance_term(self, dists, ztor):
          """
          Returns the hanging wall distance scaling term (equation 7, page 146)
          """
          fhngr = np.ones_like(dists.rjb, dtype=float)
          idx = dists.rjb > 0.
          if ztor < 1.:
              temp_rjb = np.sqrt(dists.rjb[idx] ** 2. + 1.)
              r_max = np.max(np.column_stack([dists.rrup[idx], temp_rjb]),
                             axis=1)
              fhngr[idx] = (r_max - dists.rjb[idx]) / r_max
          else:
              fhngr[idx] = (dists.rrup[idx] - dists.rjb[idx]) / dists.rrup[idx]
          return fhngr